How to Use1) Enter the fuel price displayed at the pump in the "Fuel Price" box eg. $1.555/L, $3.467/gal2) Enter the fuel discount offered in the "Fuel Discount" box eg. $0.08/L, $0.1/gal3) Enter the cash amount you wish to spend in the "Spend" box eg. $50.024) Fill the vehicle with the cash amount stated in the "Pump Display" box eg. $52.735) Optionally switch to a volume result by pressing the "Pump Display" box eg. 33.91L